Blender Eevee Vector Motion Blur?
You can use a mix of both renderers to get a mask. The Cycles scene would be super extra low fi to give you a fast render, and then you grab the Vector and the Depth from it and use it on the Composite screen to mix with your new Eevee render.
Here is one example of how to do it:
http://blenderboydiaries.blogspot.com/2019/01/how-to-get-motion-vector-blur-in_17.html